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Unlike their glass reinforced counterparts, microstructure and dynamic fracture behavior of natural fiber-reinforced thermoplastics have hardly been investigated. Here, we characterize the microstructure of cellulose fiber-reinforced polypropylene and determined its effect on impact toughness. Fiber lengths were reduced by one-half when compounded in a high-intensity thermokinetic mixer and then injection molded. At low fiber contents, injection molded specimens showed little fiber orientation; at high fiber contents, a layered structure arose exhibiting differing fiber orientations...

Dynamic mechanical analysis was employed to evaluate the performance of various natural fibers in high-density polyethylene composites. Kenaf, newsprint, rice hulls, and wood flour were sources of fiber. Composites were made at 25 percent and 50 percent by weight fiber contents. Maleic anhydride modified polyethylene was also added at 1:25 ratio to the fiber. Temperature scans in the range of -110° to +100°C were performed, and storage modulus, loss modulus, and mechanical loss factor (tan 6) were recorded over the selected temperature range. Different transitions were monitored, and the...

Woodfiber-thermoplastic composites (WPC) have received considerable attentions from the forest product industry for civil engineering applications due to its superior properties over wood and plastics alone. Particularly WPCs can be easily fabricated using traditional plastic processing techniques. The major limitation in the applications of WPCs is the poor understanding of their mechanical properties and especially the environmental impacts on these properties. The aim of this research is to systematically study the mechanical properties of aspen-fiber polypropylene composites (APCs),...

Some engineered wood fiber (EWF) surfaces on playgrounds are soft and uneven, which creates difficulties for those who use mobility aids, such as wheelchairs and walkers. The outdoor field testing reported in this study is part of an effort to stabilize EWF to improve accessibility. The concept is to mix a binder with the upper surface of EWF to create a stiff (firm) and scuff-resistant (stable) composite overlayer. Latex, silicone, and polyurethane binders were evaluated on small plots during a 6-month outdoor trial in Wisconsin. Tests were performed at regular intervals to provide a...

The paper reviews the processing advantages and challenges of microcellular injection molding and presents recent research results on applications of nanocomposites and woodfiber-plastic composites as well as new process develop for the microcellular injection molding process. In particular, two types of polyamide (PA-6) neat resins and their filled counterparts, such as a PA-6/ montmorillonite nanocomposite, a cellulose- fiber-reinforced PA-6 composite, and a hybrid PA- 6/cellulose/Wollastonite composite, were injection molded into ASTM test-bar samples with both conventional and microcell...

During outdoor exposure, woodfiber-plastic composites (WPC) are subject to biological, moisture, and ultraviolet (UV) degradation. The purpose of laboratory evaluations is to simulate outdoor conditions and accelerate the testing for quicker results. Traditionally, biological, moisture, and W laboratory tests are done separately, and only combined in outdoor field exposure. This research evaluates WPCs exposed to a combination of UV, moisture, and fungal degradations. Due to the slow moisture sorption of WPCs, the ASTM D 1413 standard laboratory soil block test was modified to include...

The technique of selective 13C-enrichment of specific carbons in lignin combined with 13C-NMR differential spectrometry between spectra of 13C-enriched and unenriched lignins (Ä13C-NMR) provides definitive information on the structure of the lignin macromolecule. Improvements were made on, (1) specific 13C-enrichment of almost all carbons involved in inter-unit bonds and functional groups in lignin, (2) estimation of the frequencies of bonds and functional groups using Ä13CNMR under quantitative conditions, and (3) detection of specifically 13C-labeled carbons by 2D- ifference spectra. A...

Kinetic and reaction mechanism of non-phenolic lignin model compounds under anaerobic polyoxometalate (POM), Na5(+1.9)[SiV1(-0.1)MoW10(+0.1) 40], bleaching conditions were examined. Analyses using a syringyl type model, 1-(3,4,5-trimethoxyphenyl)ethanol (1), a guaiacyl type, 1-(3,4- imethoxyphenyl)ethanol (2), and 1- (4-ethoxy-3,5-dimethoxyphenyl)ethanol (3) suggest the significance of steric factor in POM oxidation of these compounds. A kinetic isotope effect was observed in isotope labeling experiments. It is suggested that the rate-determining step of POM oxidation of non-phenolic...

Data is presented on chemical and physical changes observed on a series of 15 specially made writing papers as part of the development of the new ASTM standard D6789-02. Papers were exposed to north window, fluorescent, and halogen illumination for several years. Furnish covered the span from stone groundwood to textile cotton, pH 5 to 8.1, with and without alkaline reserve. Degree of polymerization was dramatically reduced, even for the most robust papers under the mildest illumination. All mechanical properties were degraded, lignin aromatic structures were destroyed, and C=O bonds...

Between 1985-1995 a substantial number of multifamily housing units in the Eastern and Southern U.S. experienced problems with thermally degraded fire-retardant-treated (FRT) plywood roof sheathing. A series of studies conducted at the USDA Forest Service, Forest Products Laboratory (FPL), examined the materials, chemical mechanisms, and process implications and has developed both practical and theoretical solutions for controlling strength effects during treatment and processing and for minimizing strength loss in-service. In addition to a series of technical publications, FPL research...